The MPLS WG Archive

["Stefan Winter" <mail@stefan-winter.de>]

Hello!

During implementing a management agent for the MPLS-LSR-STD-MIB a minor
missing feature in the MIB showed up (at least in my understanding).
The issue is about InSegments. When generating a new InSegment, one must
specify the type of label, "generic","atm" or "frame relay". The type of
label cannot be directly read. The current way to do so is to lookup the
mplsInSegmentInterface column of the row, then look into IF-MIB::ifType.x
and evaluate the ifType to guess which of the three is appropriate. Apart
from the fact that looking up content of another MIB may be expensive, it
not at always possible to determine the type of label. If, for example,
ifType reports that the device is an ATM device, both the "atm" or the
"generic" label types are possible (since "generic" is always an option).
To overcome that limitation, two options seem to be possible.
a) extend the mplsInterfaceTable with a column mplsInterfaceLabelType
b) extend the mplsInSegmentTable with a column mplsInSegmentLabelType

where b) is a more general solution as it allows to specify the type
per-label and not only per-interface, as solution a) would do. The Syntax
for such a column could be INTEGER { gen(0), atm(1), frame-relay(2) }.
And as I write this, I realize that even OutSegments need to have the type
of label specified... so the same limitation applies to OutSegments, too.

These are just my 2 cents from an implementor´s view, a comment would be
nice.

Greetings,

Stefan Winter